Small clusters of unvaccinated children are sustaining measles transmission across upstate New York, despite high overall vaccination rates, raising concerns about hidden vulnerabilities exposed by recent outbreaks.
Measles cases are appearing across upstate New York, and public health experts say the pattern highlights a problem that countywide averages can hide: small pockets of under-vaccinated children that are enough to sustain transmission.
A new study, covering data from 2013 to 2025 across 45 states, 13,000 school districts and 50,000 schools, found that the average share of people susceptible to measles doubled from 5% to 10% after the COVID-19 pandemic. Ana Bento, an assistant professor at Cornell University and one of the authors, told the Times Union that the issue is one of scale, meaning that even when overall coverage looks strong, a cluster of unvaccinated children can still give the virus room to spread.
That concern is already showing up in New York. The state Department of Health said in an Aug. 21 advisory that cases have been confirmed since July 13 in Allegany, Chenango, Madison, Otsego, Seneca, Steuben and Tioga counties. Wild-type measles has also been detected in wastewater in Montgomery and Yates counties, while unverified reports have circulated in other parts of the state.
State figures show 51 measles cases so far this year, including six in New York City and 45 elsewhere in the state, already exceeding last year’s total of 48. That is still far below the more than 1,000 cases seen in New York’s 2018-19 outbreak, but the disease remains extremely contagious. The Department of Health says one infected person can pass measles to 90% of susceptible people nearby.
Vaccination data helps explain why experts are paying close attention. The state says the MMR vaccination rate for children under 2 stood at 80.9% statewide as of Jan. 1, 2026, while kindergarten immunisation rates were 97% in public schools. Bento said New York’s 2019 ban on non-medical exemptions for school vaccines gave the state some protection, but not enough to act as a “force field” against outbreaks when local gaps remain. She said the current situation may be a warning that if other vaccine rates fall, more outbreaks could follow.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
